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x86-64 memcmp/wmemcmp: Properly handle the length parameter [BZ# 24097] 

On x32, the size_t parameter may be passed in the lower 32 bits of a
64-bit register with the non-zero upper 32 bits.  The string/memory
functions written in assembly can only use the lower 32 bits of a
64-bit register as length or must clear the upper 32 bits before using
the full 64-bit register for length.

This pach fixes memcmp/wmemcmp for x32.  Tested on x86-64 and x32.  On
x86-64, libc.so is the same with and withou the fix.

	[BZ# 24097]
	CVE-2019-6488
	* sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S: Use RDX_LP for
	length.  Clear the upper 32 bits of RDX register.
	* sysdeps/x86_64/multiarch/memcmp-sse4.S: Likewise.
	* sysdeps/x86_64/multiarch/memcmp-ssse3.S: Likewise.
	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memcmp and
	tst-size_t-wmemcmp.
	* sysdeps/x86_64/x32/tst-size_t-memcmp.c: New file.
	* sysdeps/x86_64/x32/tst-size_t-wmemcmp.c: Likewise.
This commit is contained in:
H.J. Lu 2019-01-21 11:25:56 -08:00
parent 97700a34f3
commit b304fc201d
7 changed files with 127 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
ChangeLog
View File

@ -1,3 +1,16 @@
2019-01-21 H.J. Lu <hongjiu.lu@intel.com>
[BZ# 24097]
CVE-2019-6488
* sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S: Use RDX_LP for
length. Clear the upper 32 bits of RDX register.
* sysdeps/x86_64/multiarch/memcmp-sse4.S: Likewise.
* sysdeps/x86_64/multiarch/memcmp-ssse3.S: Likewise.
* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memcmp and
tst-size_t-wmemcmp.
* sysdeps/x86_64/x32/tst-size_t-memcmp.c: New file.
* sysdeps/x86_64/x32/tst-size_t-wmemcmp.c: Likewise.
2019-01-21 H.J. Lu <hongjiu.lu@intel.com>
[BZ# 24097]

7
sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
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@ -58,9 +58,12 @@
.section .text.avx,"ax",@progbits
ENTRY (MEMCMP)
# ifdef USE_AS_WMEMCMP
shl $2, %rdx
shl $2, %RDX_LP
# elif defined __ILP32__
/* Clear the upper 32 bits. */
movl %edx, %edx
# endif
cmpq $VEC_SIZE, %rdx
cmp $VEC_SIZE, %RDX_LP
jb L(less_vec)
/* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */

9
sysdeps/x86_64/multiarch/memcmp-sse4.S
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@ -42,13 +42,16 @@
.section .text.sse4.1,"ax",@progbits
ENTRY (MEMCMP)
# ifdef USE_AS_WMEMCMP
shl $2, %rdx
shl $2, %RDX_LP
# elif defined __ILP32__
/* Clear the upper 32 bits. */
mov %edx, %edx
# endif
pxor %xmm0, %xmm0
cmp $79, %rdx
cmp $79, %RDX_LP
ja L(79bytesormore)
# ifndef USE_AS_WMEMCMP
cmp $1, %rdx
cmp $1, %RDX_LP
je L(firstbyte)
# endif
add %rdx, %rsi

7
sysdeps/x86_64/multiarch/memcmp-ssse3.S
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@ -33,9 +33,12 @@
atom_text_section
ENTRY (MEMCMP)
# ifdef USE_AS_WMEMCMP
shl $2, %rdx
test %rdx, %rdx
shl $2, %RDX_LP
test %RDX_LP, %RDX_LP
jz L(equal)
# elif defined __ILP32__
/* Clear the upper 32 bits. */
mov %edx, %edx
# endif
mov %rdx, %rcx
mov %rdi, %rdx

4
sysdeps/x86_64/x32/Makefile
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@ -6,9 +6,9 @@ CFLAGS-s_llround.c += -fno-builtin-lround
endif
ifeq ($(subdir),string)
tests += tst-size_t-memchr
tests += tst-size_t-memchr tst-size_t-memcmp
endif
ifeq ($(subdir),wcsmbs)
tests += tst-size_t-wmemchr
tests += tst-size_t-wmemchr tst-size_t-wmemcmp
endif

76
sysdeps/x86_64/x32/tst-size_t-memcmp.c Normal file
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@ -0,0 +1,76 @@
/* Test memcmp with size_t in the lower 32 bits of 64-bit register.
Copyright (C) 2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#define TEST_MAIN
#ifdef WIDE
# define TEST_NAME "wmemcmp"
#else
# define TEST_NAME "memcmp"
#endif
#include "test-size_t.h"
#ifdef WIDE
# include <inttypes.h>
# include <wchar.h>
# define MEMCMP wmemcmp
# define CHAR wchar_t
#else
# define MEMCMP memcmp
# define CHAR char
#endif
IMPL (MEMCMP, 1)
typedef int (*proto_t) (const CHAR *, const CHAR *, size_t);
static int
__attribute__ ((noinline, noclone))
do_memcmp (parameter_t a, parameter_t b)
{
return CALL (&b, a.p, b.p, a.len);
}
static int
test_main (void)
{
test_init ();
parameter_t dest = { { page_size / sizeof (CHAR) }, buf1 };
parameter_t src = { { 0 }, buf2 };
memcpy (buf1, buf2, page_size);
int ret = 0;
FOR_EACH_IMPL (impl, 0)
{
src.fn = impl->fn;
int res = do_memcmp (dest, src);
if (res)
{
error (0, 0, "Wrong result in function %s: %i != 0",
impl->name, res);
ret = 1;
}
}
return ret ? EXIT_FAILURE : EXIT_SUCCESS;
}
#include <support/test-driver.c>

20
sysdeps/x86_64/x32/tst-size_t-wmemcmp.c Normal file
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@ -0,0 +1,20 @@
/* Test wmemcmp with size_t in the lower 32 bits of 64-bit register.
Copyright (C) 2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#define WIDE 1
#include "tst-size_t-memcmp.c"